Recent evidences have shown that the human malaria parasite Plasmodium ovale exists as two non-recombining species, sympatric in many countries.

New nested PCR assays targeting three different gene loci (Potra, Pog3p and Porbp) and real-time quantitative PCR assays for discriminating between Plasmodium ovale curtisi and Plasmodium ovale wallikeri have been developed and deployed in the field for species discrimination. Furthermore, we are investigating the possible barriers (biological, epidemiological and geographical) which keep these two species apart, when they occur together in much of tropical Africa and Asia. Recently, we have shown from analysis of samples and data from the MRL archives that there is a significant difference in the latency period between Plasmodium ovale curtisi and Plasmodium ovale wallikeri. We are currently investigating the possible barriers to inter-species mating and recombination betweenthe two species by looking at divergence of genes involved in fertilization. We have recently begun to evaluate both species by in vitro culture, and to test for sensitivity to a range of antimalarial drugs.